1. Field of the Invention
The present invention relates to a method and device for preparing platinum catalyst, especially relates to a method and device for preparing platinum catalyst with modified reaction pressure.
2. The Prior Arts
Fuel cells are capable of providing high energy efficiency and relatively rapid start-up. Moreover, fuel cells are capable of generating power without generating the types of environmental pollution that characterize in many other sources of power. Thus, fuel cells can be a key to substituting conventional power sources, meeting critical energy needs while also mitigating environmental pollution. Fuel cells are electrochemical devices that convert chemical energy directly into electrical energy without combustion. The combination of high efficiency, low environmental impact, and high power density has been and will continue to be the driving force of vigorous researches, dedicated to apply fuel cells in areas such as transportation, residential power generation, and portable electronic applications.
For fuel cells, platinum (Pt), ruthenium (Ru) and their alloy are mainly used as the catalysts in the electrochemical reaction. Currently, chemical reduction and electrodeposition are the most common methods for preparing catalysts, which are a part of electrodes. Chemical reduction method is typically utilized by immersing a catalyst support in the catalyst precursor solution followed by heating the catalyst precursor solution to a predetermined temperature. During the heating process, the catalyst precursor solution starts to boil and produce water vapor at the boiling point. The water vapor then condenses through a condenser and flows back to the original catalyst precursor solution to maintain the ratio of water to reducing agent, which is also called reflux method. In the meantime, catalyst reduces gradually on the catalyst support. Compare to the electrodeposition method, the chemical reduction method is not only easier to operate under simple experiment conditions, but also smaller size of catalysts can be obtained.
However, the traditional chemical reduction (or reflux) method requires about 3-8 hours to complete the catalyst preparation, which is a time-consuming work. Wu et al. (Science in China Series E: Technological Sciences January 2010, Volume 53, Issue 1, pp. 264-271) performed the reduction process under high pressure (1 MPa, or 10 atm) for 8 hours. Accordingly, it is essential to simplify the preparation conditions of the chemical reduction method with superior catalyst characteristics (size, uniformity and electrochemical property).